Đáp án:
Giải thích các bước giải:
a) $\dfrac{3}{4}$+$\dfrac{2}{5}$+$\dfrac{1}{4}$+$\dfrac{3}{5}$
=($\dfrac{3}{4}$+$\dfrac{1}{4}$)+($\dfrac{2}{5}$+$\dfrac{3}{5}$
=$\dfrac{4}{4}$+$\dfrac{5}{5}$
=1+1
=2
b)$\dfrac{2}{3}$x$\dfrac{3}{4}$x$\dfrac{4}{5}$x$\dfrac{5}{6}$
=($\dfrac{2}{3}$x$\dfrac{3}{4}$)x($\dfrac{4}{5}$x$\dfrac{5}{6}$)
=$\dfrac{1}{2}$x$\dfrac{2}{3}$
=$\dfrac{1}{3}$
c) $\dfrac{4}{5}$-$\dfrac{2}{3}$+$\dfrac{1}{5}$-$\dfrac{1}{3}$
=($\dfrac{4}{5}$+$\dfrac{1}{5}$)-($\dfrac{2}{3}$+$\dfrac{1}{3}$)
=$\dfrac{5}{5}$-$\dfrac{3}{3}$
=1-1
=0
